I have a 2007 suburban with a 5.3L engine. It was ticking so I replaced the lifters. I did not remove the cam shaft or timing chain when I did the lifter replacement. so I am ruling out a timing issue. I checked compression on all cylinders and they were all between 160 to 170 psi. I can’t remember exactly but there was nothing that seemed troubling. I checked vacuum from the brake booster hose and there I found something interesting. Not exactly sure what it tells me. Can you help interpret these results? I’ll attach a video file. Also, after about 5 minutes the popping sound goes away, but still low vacuum.

Thanks in advance.

 

Attaching the video doesn’t seem to be working. See if this picture works.
vacuum stays around 13 in. Hg. Drops to 11 or 12 when it makes the popping noise. After it’s warmed up, more like 14 to 15 in. Hg. And no popping.

 

 

I think you have an intake leak somewhere..

 

Should always replace cam when doing lifters...